Most energy produced today is derived from fossil fuels such as oil, coal and natural gas. However, these energy sources all have significant disadvantages including pollution, periodic shortages and escalating costs of extracting the fuels. Although at one time it was thought that nuclear fission power could provide an answer to these problems, that has not proved out. Not only are there significant concerns regarding the safety of operating the existing nuclear systems, but there is also the significant problem of the safe transportation and long term storage of the spent fuel.
By contrast, solar, wind and hydro energy systems all offer the advantages of being relatively safe and reliable. Moreover, these technologies have the common advantage of drawing their power from sources that are virtually inexhaustible. However, that is not to say these technologies are without difficulties. For example, one difficulty with these technologies is that the underlying energy sources (i.e., wind, sunlight and water) can be subject to periodic swings in availability, e.g., the sun may eclipse, the winds may subside, and the water levels may fall due to extended periods of drought. Another difficulty is that the best locations for capturing the foregoing energy sources are often remote from where the energy is used. This is especially the case for large scale hydro power installations.
Traditionally, most wind, solar and hydro power installations (particularly large scale, commercial operations) rely on utility grids for transferring the generated energy to where it will be used. However, this may not be the most efficient use of the generated energy from an economic standpoint. As is well known, connecting a wind or hydro powered turbine generator to a utility grid imposes certain constraints on the generator. For example, the power output of the generator must be synchronized (i.e., in phase) with the utility's grid supply. With synchronized generators, this is accomplished by controlling the rotor speed of the turbine to exactly match the utility supply frequency. Another constraint with relying solely on a utility grid as a carrier of the generated energy is that there may be a low demand on the grid at the same time there is ample capacity to generate additional power. When this occurs, the energy that could be captured is simply wasted. Although various energy storage systems (e.g., battery storage or pumped hydro-energy storage) can be utilized to overcome this problem, such systems are relatively expensive to install and result in efficiency losses of their own due to the repeated energy conversions.
Although most large scale solar, wind and hydro generating installations rely solely on utility grids for transporting the energy to where it is used, some installations use other means. In particular, it is known to use the electrical energy from solar, wind and hydro installation to electrolyze water to produce hydrogen, which is then collected and transported offsite (e.g., by vehicle, rail, ship or pipeline) where it is typically burned or used in a fuel cell. As one example, U.S. Pat. No. 5,592,028 discloses a wind farm generation system that utilizes homopolar direct current (“DC”) generators to electrolyze water into hydrogen and oxygen for transportation offsite. As another example, U.S. Pat. No. 4,910,963 discloses a solar energy collection system that produces electric current for powering an electrolysis unit and a cryogenic cooling unit which produces liquid hydrogen and oxygen. Specific to the hydroelectric field, U.S. Pat. No. 6,104,097 discloses a submersible hydro turbine designed for placement in river or ocean currents. The submersible hydro turbine includes a water tight bulb housing which contains everything necessary for the production of hydrogen gas including a turbine runner connected to an AC generator, an electrical converter that produces DC power from the AC power, and an electrolyzer which produces hydrogen and oxygen gas from the DC electrical power. The hydrogen is collected within the watertight housing and then piped to an on-shore storage tank for transportation offsite.
Although using hydrogen as a carrier of energy generated from solar, wind and hydro installations avoids the aforementioned constraints imposed by using a utility grid to carry the energy, it also may not be the most efficient use of the generated energy from an economic standpoint. As is well known, the prices of electrical energy continuously fluctuate due to changing demand levels, both due to seasonal variations and time of day restrictions. Similarly, the price of hydrogen is also impacted by changing demand levels and seasonal variations. As such, there are times when it may be more profitable to utilize the generated electrical energy to produce hydrogen on-site rather than to channel the power onto the utility grid, while at other times the reverse may be true.
In view of the foregoing, it can be seen there is a need for hydro power installations that are capable of large scale continuous hydrogen production. There is also a need for hydroelectric power installations that provide operators with information that facilitates intelligent decisions on operating the installation in an operating mode that maximizes revenue as market conditions change.